When choosing materials for vacuum systems, it’s crucial to minimize gas loads while ensuring the material’s strength. Stainless steel and aluminum are common choices, with stainless steel often preferred for its lower outgassing rates. It’s important to consider factors like surface finish, outgassing, and permeation, and to avoid materials that might release gases under vacuum. Proper selection of sealing materials is also essential to maintain vacuum integrity.
Metals the most prevalent choice of vacuum chamber materials, with stainless steel (SS) far ahead of other metals such as mild steel. For example, deciding to use SS doesn’t mean any and all SS alloys. Free-machining alloys such as 303 SS contain sulfur (S), but the vapor pressure of the sulfur (S) is too high for high vacuum systems. 304 SS, though, is the most common choice. This helps narrow things down, but for ultrahigh vacuum (UHV) the low-carbon 304L alloy is recommended.
Historically, the following three factors have made stainless steel the preferred material for the manufacture of vacuum chambers.
